Manufacturers of nonroad diesel engines are expected to meet set emissions regulations. For example, Tier 3 emissions regulations required an approximate 65 percent reduction in particulate matter (“PM”) and a 60 percent reduction in nitrogen oxides (“NOx”) from 1996 levels. As a further example, Interim Tier 4 regulations required a 90 percent reduction in PM along with a 50 percent drop in NOx. Still further, Final Tier 4 regulations, which will be fully implemented by 2015, will take PM and NOx emissions to near-zero levels. Manufacturers of maritime engines are also expected to meet emissions regulations though they vary from the nonroad emissions regulations (e.g., International Maritime Organization regulations).
One approach for potentially aiding in meeting emissions regulations is to increase the fuel rail pressure in the engine. Some pumps that operate at these increased pressures impose high cyclic torque loads on surrounding engine gear train components. High cyclic torque may cause an increase in gear noise and failures.